The present invention relates to fuel cells and, more particularly, to a sensor plate for measuring an operating parameter such as current or temperature of a cell in a fuel cell stack.
Fuel cell stacks are electro-chemical energy conversion devices that use a hydrogen fuel and oxygen to produce electricity with water and heat as by-products. A fuel cell stack typically includes a plurality of individual fuel cells arranged in a stacked relation. Each fuel cell includes an anode flow field plate, a membrane electrode assembly (MEA) and a cathode flow field plate. A coolant layer may optionally be included.
An oxidant gas, such as oxygen or air, is supplied to the cathode flow field plate. A fuel, such as hydrogen, is supplied to the anode flow field plate of the fuel cell. As the hydrogen gas flows through the anode flow field plate, the hydrogen gas is separated on an anode catalyst on the MEA into positively charged hydrogen ions and negatively charged free electrons. The hydrogen ions pass through a proton exchange member (PEM) of the MEA where the ions combine with oxygen on a cathode catalyst to produce water. When multiple fuel cells are used to form a stack, the electricity produced by each cell is transmitted through the fuel cell stack and collected by external circuitry. Since the reaction which takes place in the fuel cell stack is exothermic, a coolant layer may be used to remove heat from the fuel cell by supplying and exhausting a coolant fluid.
Various flow field plate designs have been used to form fuel cells with the design being dictated by the particular application. To determine the efficiency of each flow field, the design is incorporated into the anode and cathode flow field plates to form a fuel cell which is then used in a fuel cell stack. Determining the current distribution and temperature distribution at various locations within the flow field can provide insight into the effectiveness of that flow field plate design. Also, certain operating conditions cause variations in the distribution of the current and temperature of a fuel cell. Knowing the current and temperature distributions during various operating conditions allow for testing of fuel cells to evaluate the efficiency of the design. Accordingly, there is a need in the art to provide an in-situ sensor plate for measuring the current and temperature distribution of an operating fuel cell.
The present invention is directed to an apparatus for measuring current and temperature distribution of an operating fuel cell within a fuel cell stack.
The present invention includes a sensor assembly having a sensor plate. The sensor plate comprises a first flow field plate segmented into an array of electrically isolated regions, a second flow field plate, and a circuit board interposed between the first and second flow field plates. The circuit board has a resistor array with a resistor associated with each of the electrically isolated regions for measuring the current and/or temperature associated with each individual segment, thereby providing a current and/or temperature distribution across the major face of the fuel cell.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples provided therein, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.